The present invention relates to a gear pump and/or motor used in hydraulic systems and more particularly to an external gear pump and/or motor wherein the radial floating of the gear shaft is achieved by floating sleeves.
There has been a rapid development in the field of gear pumps. Various technical measures, such as employment of a larger high-pressure zone and heavy-duty Du bearings, have been taken in most pumps. It can be said that there is little potentiality in improving the performance of a gear pump of conventional structure. Therefore, manufacturers of gear pumps in many countries have been studying and developing gear pumps of new structures in recent years. Most of them are of radial floating type. Although structures of various radial floating types have been disclosed in patents in many countries, radial floating is achieved through a radial floating sealing block in all these solutions without exception. More particularly, gears, gear shafts and gear bearings in these gear pumps are relatively stationary in the radial direction. Radial floating is achieved through a floating sealing block which can move radially towards the gears, and radial sealing is achieved through two sections of circumferential wall on the floating sealing block coincided with the driving gear and the driven gear respectively. A gear pump of such a radial floating type is apparently complicated in structure and has a relatively larger radial dimension.